I. Field of the Invention
The present invention relates to wireless communications. More particularly, the present invention relates to a novel and improved method and apparatus for communicating with a programmable wireless modem.
II. Description of the Related Art
As computers have gotten smaller and become increasingly portable, they have been taken out of the home, office, and school to various on the road assignments. In order to remain in contact with other computers, such as a computer network, or to communicate e-mail to other computers, the portable computers typically use modems (modulators/demodulators). The modem translates the digital signals from the computer to analog signals for transmission on an analog telephone network, and also demodulates the received analog telephone network signals into a digital form usable by the computer. However, in the broadest sense, a modem may modulate and demodulate information to and from any predetermined communication formats, whether they be digital or analog in nature. It is in this broadest sense that the word "modem" is intended to be used in the present invention.
A portable computer must be able to keep in contact with other computers without having to be physically connected to a standard hardwired telephone line. This portability is accomplished by connecting the computer modem to a wireless radio frequency (RF) transceiver. One form of such a wireless transceiver is a cellular radiotelephone. A number of competing cellular systems are now available. These include the analog advanced mobile phone system (AMPS), time division multiple access (TDMA), and code division multiple access (CDMA), the last two systems being digital systems. CDMA provides a distinct advantage in cellular data communications. A radiotelephone, however, can be bulky and unwieldy to connect to a computer. Since the user interface portion of the radiotelephone is not strictly necessary for computer data communication, the portion of the radiotelephone utilized in the subject invention can be made much more compact and portable by eliminating hardware, such as the keypad, display, battery, microphone and speaker. Such a reduction in bulk makes it possible to fit the components of a radiotelephone onto a circuit card (such as PCMCIA) that is inserted in a computer's I/O slot, or is directly built into the computer.
The drawback of not having a user interface on the radiotelephone is the inability to program many user-specific features of the radiotelephone that are normally programmed by entering a specific key sequence on the keypad. These features may include, for example, switching between Mobile Identification Numbers (MINs) to avoid roaming charges, storage of phone numbers, call forwarding, call waiting, and long dual tone multiple frequency (DTMF) tones to access certain answering machines. There is a resulting need for a way to program these types of features into a small portable wireless modem communication system. Currently, integrated modem systems can't receive phone-related commands required for radio communication. The present invention allows for a continuous communication link for applications where land telephone lines cannot be used or become inoperative or unreliable.